This invention relates generally to pump assemblies. More particularly, it relates to an assembly having a pump which is adapted to be driven in two speed ranges, with a shift from one range to the other being effected automatically in response to attainment of a predetermined pump pressure. The assembly automatically is recycled for operation in the original range when pump pressure drops to another predetermined level.
Automotive manufacturers, in particular manufacturers of diesel engines, are faced with the problem of fuel pumps which deliver low capacity at engine cranking speeds. One solution to such a problem would be to drive two fuel pumps at engine cranking speeds, and to provide some way to cut off one of them after engine start-up. Obviously, the necessity of providing two pumps and suitable control apparatus is both costly and inefficient.
There remains a need in the art for a simple, inexpensive two-speed pump assembly which will deliver fluid at a relatively high capacity initially and which will shift automatically to deliver fluid at a relatively low capacity after the initial need has been met.